This invention relates to articles which include a core and extending over one or more sides of the core a covering or skin. Laminated plastic structures of this description are used as recreational products, as exemplified by so-called bodyboards, which are used to ride on the waves in ocean surf.
A typical bodyboard has a core of stiff material, and this core might take the form of a plank of semi-rigid foam. The foam composition of the core provides necessary flotation. The core normally is covered over opposite sides with what are commonly referred to as skins. The skin which extends over the downwardly facing surface of the core, and that forms the bottom of the bodyboard, functions to provide protection for the inner core and also to provide a slippery surface, whereby the board moves through the water with minimal drag. The skin that extends over the opposite upper surface of the core, and which forms the top surface of the board, also provides the function of protecting the core which forms the board interior. Since this upper surface of the bodyboard is the surface which the user bears against when using the board, it is desirable for reasons of comfort and ease of use that this covering having a degree of softness not necessarily required in the skin that forms the bottom of the board. Furthermore, the skin on the top of the board, since it is not traveling through the water, but is supporting the user, should not be as slick as the bottom-forming skin, but have a textured quality, enhancing frictional contact with the user, so that the user does not slide off too easily.
Amusement devices, such as bodyboards, not infrequently have printed logos, art designs, or other forms of graphics portrayed on surface skins in the product. It is obviously advantageous in the manufacture of boards and like products that graphics of this description be produced in a durable manner, with the graphics being scratch-resistant and wear-resistant.
In general term, this invention concerns an improved construction for the skin covering a core in an article, such as a bodyboard, where the skin includes a thin layer of foam produced by expanding a foam-producing heat-expandable matrix layer, and the skin further includes, integrated with this foam, the residue of a polyolefin film earlier applied to cover the matrix layer, this film having softened during formation of the foam layer and after softening, traveling into the foam to integrate with the foam. The skin described is tough and wear-resistant. The skin may be prepared with a degree of softness promoting body comfort. The skin further is producible with a tactile texture on the outer surface, which is the natural surface texture of the foam produced by foaming of the matrix layer, this textured characteristic reducing the slipperiness of the skin when used for a covering such as in a bodyboard.
Another object of the invention is to provide improvements in the skin covering a core, featuring graphic imaging material incorporated into the skin in a novel manner that imparts substantial abrasion and wear resistance to the graphics portrayed.
Yet another object is to provide a core and skin covering combination which includes graphics incorporated with the skin, where the imaging material producing the graphics is an integral part of the foam which forms the covering skin.
Yet a further object is to provide a novel core and skin covering combination, where the skin is produced by providing a matrix layer of heat-expandable foam-producing polyolefin, and further providing a film disposed over the outer face of this matrix layer, this film having graphic imaging material incorporated in its interior. With heat applied, the matrix layer expands to produce a foam, and the film softens with the residue of the film together with the imaging material migrating over the surface of the foam produced by expansion of the matrix layer.
In a preferred embodiment of the invention, the polyolefin film which is applied over the matrix layer comprises inner and outer film layers, with the graphic imaging material extending as a deposit in the interface between the film layers. To obtain images in the final product which are sharp, distinct, clearly visible and attractive, excellent results are obtained by utilizing as the inner of the film layers a film layer which is non-light transmitting and opaque, preferably white, and using as the outer film layer, a clear non-opaque polyolefin material.